ct7-aja2 motherboard checksum error

Hi

I have had the motherboard (as header) for about 2 years now and i find it
goes through a CMOS battery once a year, giving the checksum error when it
is flat. On other mobo's i have found they normally last 3 or 4 years at
least but the batteries are cheap enough so it is not a problem.

I have just changed it again but this time i am still getting the error
message Chaintech say it is poor contacts on the battery or the CMOS jumper.
I have cleaned these the best i can but it has not made any difference. It
only reports the error message when it has been off for a while (ie
overnight).

Could there be another reason for this or is it possilby a faulty
motherboard (has anyone come across this before).

thanks

Gary